Ceramic fibers modules have replaced insulating firebrick as the material of choice for lining heat treating furnaces , ceramic kilns, brick kilns and other kinds of furnaces. Blankets of alumina-silica fibers are cut into strips or folded and edge-stacked to form the modules which can then be attached to the shell of a furnace by anchors, pins, cement or a combination of these and other means.
Although such edge grained modules are advantageous because of their light weight, ease of handling, and adaptability, the nature of their construction poses certain problems such as opening of the seams upon shrinkage at high temperature. The passage of corrosive gases from the interior of the furnace through such open seams to the furnace wall will shorten the life of the furnace. Also, the difficulty in hiding the attachment hardware away from such corrosive gases while keeping it accessible to the installer's hands is generally recognized.
Several module designs and retaining systems have been proposed to utilize the advantages and make it easier to install the modules in a furnace. Finney, in U.S. Pat. No. 4,516,374, teaches an intermodular mounting system wherein an elongated retainer bar extends laterally through a module and is supported at each end by bifurcated supports extending inward from the furnace wall along opposite margins of the module. The fingers of the bifurcated supports are bent toward each other to grip end portions of retainer bars projecting from adjacent modules and must be pried apart to release the bars when a module is to be removed.
In U.S. Pat. No. 4,574,995, Sauder et al teaches the parquet arrangement of a plurality of edge-grained ceramic fiber modules to minimize the occurrence of cracks resulting from the high temperature shrinkage of the fibers. A supporting member embedded in the cold face of a module extends through a block of backing type insulation and is welded to the furnace wall by pushing a welding gun through the module until it finds and engages the supporting member and triggering the gun.
Pickles, in U.S. Pat. No. 4,157,001, teaches an anchoring system for insulating material on a high temperature furnace wall wherein a stud having a plurality of anchor-engaging notches is attached to the wall and a first anchor having an open, tapered cavity therein is pushed axially over the projecting end of the stud and through the insulating material to engage a first pair of notches on the stud and hold the material between the anchor and the wall. A second anchor is partially inserted axially into the cavity of the first anchor to engage a second pair of notches on the stud more distant from the wall than the first pair.
Herring, in U.S. Pat. No. 4,494,295, teaches a furnace wall lining system wherein a plurality of brackets, each having its free end bent into a loop, is welded to the furnace wall according to a predetermined pattern to accommodate the required number of ceramic fiber modules, a module is then laid against the wall and next to a bracket, and a retainer pin is pushed through the loop of the bracket and into the module as far as a stop on the pin will allow. Another module is then impaled on the portion of the retainer pin which still sticks out of the loop and the sequence is repeated. The first and last module in each course must be impaled on pins projecting from the end walls of the furnace.
A retainer assembly for securing a ceramic fiber blanket against a furnace wall is taught by Hanson et al in U.S. Pat. No. 4,576,532. The assembly consists of a notched, elongated stud having a longitudinal slit and a retainer plate which engages the notches of the stud. A bend in the stud and the slit form a pair of laterally offset fingers having alternate teeth and notches opposite the slit. When an array of studs is welded to the furnace wall, a blanket is impaled on them and made to lie against the furnace wall. The retainer plates each have a central opening whereby they are slidably received by the studs whose fingers move in a scissor-like fashion as the plates are urged along the studs toward the blanket. When a plate is in the desired position against the blanket and with respect to the notches, the fingers are allowed to scissor back toward their original position whereby the plate is locked in that position by the teeth on the fingers. The bifurcated stud of Hanson et al is used in a novel combination with a tine in the invention described and claimed herein. Although the stud is described herein below in association with the other features of this invention, the description of the stud in U.S. Pat. No. 4,576,532 is incorporated herein by reference.